Boron carbide compound



Patented Aug. 16, 1949 UNITED STATES PATENT OFFICE No Drawing.

Application May 27, 1946,

Serial No. 672,701

1 Claim. 1

This invention relates generally to the class of metallurgy and is'directed particularly to a compound, and method of using the same, whereby certain characteristics of iron base alloys are desirably changed.

The present invention has to do with the mixing in iron base alloys, of boron carbide in proportions greater than can be obtained by present generally known and followed methods, whereby there may be produced, as a principal object of the present invention, an iron base alloy having greater wear and acid resistance.

Another object of the invention is to provide a novel compound or mixture which makes possible the introduction of boron carbide into iron base alloys in quantities ranging from /2% to of the total iron alloy mix.

A further object of the invention is to provide an improved method of mixing boron carbide in iron base alloys whereby, by the difiusion of the boron carbide through the mixture in greater proportions than can be accomplished according to known metallurgical processes, it is possible to reduce to a considerable extent the quantity of such scarce elements as chromium and tungsten in the alloy and at the same time produce an alloy having greater wear resisting qualities than alloys using large percentages of chromium and tungsten.

In accordance with the present invention the improved iron base alloy is produced by the introduction into the furnace melt at the proper moment, of the desired quantity of boron carbide, hydrogen reduced iron and nickel. These ingredients are thoroughly mixed together and introduced into the melt in any desirable manner or form depending largely upon the process by which the melt is produced, that is, whether it is produced in an electric furnace or in a furnace of another type. The hydrogen reduced iron and boron carbide are for all usual or ordinary alloy melts used in equal proportions in the compound regardless of the proportion of compound used to the entire melt and in the majority of cases also the nickel is used in the same quantity as the hydrogen reduced iron and the boron carbide, but the quantity of this latter ingredient may be varied in accordance with the quantity of nickel present in the alloy mixture.

The preferred form of the boron carbide compound consists of equal parts by weight of hydro gen reduced iron which is carbon free, commercially pure or approximately 99% pure nickel, and boron carbide containing not less than 70% of. boron. These ingredients of the compound are in powder form and the particle size must not be larger than sixty mesh or smaller than two hundred mesh.

The ingredients are mixed thoroughly dry and stored for use for introduction into the molten alloyed iron or steel, in suitable metal containers or in compressed pellets.

The following composition is illustrative of an alloy having as a part thereof the boron carbide compound of the present invention, together with the range of percentages of the different ingredients which may be employed for producing various grades of alloys for use as weld rods, castings or in any other desired manner.

The various grades of iron base alloys produced within the ranges set forth are not exceeded in alloy content with the successful introduction of the selected quantity of the herein described boron carbide compound.

The iron base alloy and percentage range of the constituents is as follows:

Per cent Chromium .20 to 30 Molybdenum .20 to 15 Tungsten 1.00 to 15 Nickel .50 to 8 Titanium .10 to 1 Manganese .20 to 2 Silicon .20 to 2 Boron carbide to 10- Carbon 2 to 4.

Balance, iron.

In the majority of cases use may be made of the boron carbide compound with the three ingredients thereof, that is, the hydrogen reduced. iron, nickel and boron carbide in equal proportions or equal parts by weight as above outlined.

However there are times when nickel is already a major partof the molten alloy before the boron carbide compound is introduced into the melt. Since 8% of nickel is the maximum which can be employed in the entire melt without causing embrittlement of the produced matrix, the quantity of nickel in the boron carbide compound may be reduced as necessary in order to maintain the allowable maximum quantity of nickel in the final product.

In some instances it may be necessary to em ploy the hydrogen reduced iron in about half the *weight of the boron carbide, in the mixture. This is for the reason that in sluggish mixtures of some steels and irons the boron carbide compound would not spread or mix in the molten mass quickly enough to make it uniform throughout. The hydrogen reduced iron would, however, never be reduced to less than half the boron carbide content by Weight.

While different proportions of the ingredients may be employed, the proportion of iron is never less than half of the boron carbide and the nickel is not less than 2% of the total mixture introduced into the iron base alloy melt.

Until the development of the pres'entinvention great-difficulty has always been experienced in mixing boron carbide in iron base alloys. The

maximum amount which it has been possible todiifuse through the alloy, especially-in the-electric furnace, has been about 2%.

Under the present invention it-is possibletothoroughly diffuse through the alloy. mass as. much as of boron carbide, substantiallyin stantly after its introduction into the melt, in the compound.

In accordance with the present invention, about three or four minutes, not less than three, afterthe furnace melt is ready for pouring-into,- ladies or molds, and after the molten mass has beenthoroughly degasified causing oxygen, nitrogen and-other harmful gases or impurities to-be: removed, the herein described boron carbide com,- pound is introduced inthe percentage of from 10%- to 30%- by weight of the entiremeltand the melt is thoroughly stirred or agitated for ap: proximately thirty seconds, after which it'is'readyto 1 01111;

It is understood, of course, that the proportion of the herein described compound will be governed by the wear and corrosive conditions to be met by the bodies produced from the alloy.

Theboron carbide compoundmay be submerged in the melt bymeans of tongs or like. tools, in the form of pellets or in the usual metal containers.

In cases where the alloy is not produced in an electric furnace of the agitating type the compound introduction may be accomplished by ladle induction as in those processes where the.

smelter pours directly from the furnace into a.- ladle, deoxydizing there and then pouring from the ladle into the molds.

the bottom is well covered with molten metal,- the containers of the boron carbide compound, or the pellets thereof, are dropped in and the ladle filled to capacity. No stirring is required as the mixing is thoroughly accomplishedby'the pouring action.

It will, of course, be obvious that-in following the method of mixing the compound with the metal in the ladle itis necessary, in; order that the desired result may be obtained, to use-extreme:

careiin measuring correctly both theamount-im the ladle and the amount of the compound. In

effecting the introduction of the compound into the alloy in the furnace, thisis easily accomplished but in mixing in the ladle-much-is left to-guess Work and therefore extreme; care must be used as stated.

By employing the powders of the'cornpound.v within the range of the particle size'hereinbeiore, stated, the .timeof distribution of the compound; through the mass is reduced to'a minimum.- If:

In such processes, as soon as pouring commences into the ladle and 4 not melt but appears as a very dense hard substance in minute form, increasing the hardness of the mass considerably and, due to this increased hardness, it is also found that such castings are far less subject to corrosive attack because of the fact that the boron carbide compound gives a hard surface to the product.

As previously stated .there are conditions under which it may become necessary or desirable to reduce the amount of nickel in the'boron -carbide compound, but this is never reduced to less than 2% of the total compound mixture. The amount of hydrogen reduced iron preferably is balanced with the amount of boron carbide, but may be reduced under certain conditions to not less than half theamountof boron carbide.

Prior to the development of the present invention the average of the ingredients for an iron basealloy used for the making of weld rods, castings and the like was as set forth in the following; formula;

m l Au Per-cent Chromium 30 Tungsten 22 Molybdenum 15 Nickel 10 Manganese 2 SlIiCOD. 1

Total alloy 80%, balance iron.

Use of the present boron carbide composition in any alloy of the character above set forth makes possible the reduction to a very considerable extent of the amounts of the scarce elee ments, chromium and tungsten, as shown in} the following Formula B, and produces an alloy' which outwears one made according to Formula A, by a ratio of 2 to 1.

Formula B Balance iron.

Itris to be noted that formula-B! contains much smaller amounts of chromiumandtungstcn and of certain other ingredients, but:becausel of the inclusion of the. presentboron carbide: composition the alloy produced is. ofnsuperior. quality particularly as regards itswearrand acid resisting" properties.

Tests made. upon boron carbide' containing:

alloys produced according to the single;-Formula: B here given, givea'BrineH hardness-reading of #670-680; very uniform and provingth'e metal; to be very dense and highly resistant tozweari The hardnessnumber for'an' :alloy made aocording to Formula-A was never greater-than #514 and often as low as #461, nctat'alliuniformb ln-spite-of the fact that thesalloyfi-of Formula? A? has 'high'chromium, molybdenum, .nickel andtungsten, all field orservice testshave proved that :a boron carbide containing alloy such' as set forth in Formula-B,. has, at least 50% more" resistance .to corrosive wear in all itsiformsith'an: Formula "A.

inertness. of 2:1)01011 carbideto all acids;concn-z trated and dilute and the .high degree ofahard'e:

This. is believedsto. beiduel'toz'the the iron is not less than half that of the boron l5 carbide and the nickel is not less than 2% of the total mixture.

NEVILLE JAMES BUCHANAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,913,373 De Golyer June 13, 1933 1,946,130 Comstock Feb. 6, 1934 1,973,441 Moel's et a1. Sept. 11, 1934 1,975,310 Comstock Oct. 2, 1934 2,129,347 De Golyer Sept. 6, 1938 2,169,193 Comstock Aug. 8, 1939 2,200,258 Boyer May 14, 1940 

